oslo: add hero and main images for the collection and each sub-dataset

Syncs the oslo cards and figures on the Hub with the reviewed state on GitHub (open-h/OpenH-RF).

Adds a hero image to the collection card and to each sub-dataset card, plus a `main.png` per card for the OpenH-RF collage. All images are reconstructed from the raw channel data in this folder with the `reconstruct.py` pipelines and `parameters.yaml` settings.

The collection card's hero, `assets/hero.png`, is a 7-panel collage of sub-datasets A-E and replaces the single apical four-chamber still; its caption links every source file. Each sub-card now opens with its own hero: a 50-frame cine loop for A_cardiac, a first-frame still for B-E, and for F_motion a B-mode next to the axial displacement per frame after the first push of `SWE_L7_type_III` (lag-one autocorrelation estimate, not part of the reference pipeline). The `main.png` files show the same acquisitions without axes on a black background.

**GitHub PR:**
- [tristan-deep/OpenH-RF#34](https://github.com/tristan-deep/OpenH-RF/pull/34) — oslo: add hero and main images for the collection and each sub-dataset

Files changed: 21.

```
~ oslo/A_cardiac/README.md
~ oslo/B_carotid/README.md
~ oslo/C_verasonics_phantom/README.md
~ oslo/D_alpinion_phantom/README.md
~ oslo/E_simulation/README.md
~ oslo/F_motion/README.md
~ oslo/README.md
+ oslo/A_cardiac/assets/hero.gif
+ oslo/A_cardiac/assets/main.png
+ oslo/B_carotid/assets/hero.png
+ oslo/B_carotid/assets/main.png
+ oslo/C_verasonics_phantom/assets/hero.png
+ oslo/C_verasonics_phantom/assets/main.png
+ oslo/D_alpinion_phantom/assets/hero.png
+ oslo/D_alpinion_phantom/assets/main.png
+ oslo/E_simulation/assets/hero.png
+ oslo/E_simulation/assets/main.png
+ oslo/F_motion/assets/hero.gif
+ oslo/F_motion/assets/main.png
+ oslo/assets/hero.png
+ oslo/assets/main.png
```

oslo/A_cardiac/README.md

@@ -18,6 +18,10 @@ size_categories:
 
 # USTB - In-vivo Cardiac (Verasonics P4-2)
 
+![Cine loop of a parasternal long-axis view](assets/hero.gif)
+
+*All 50 frames of [`Verasonics_P2-4_parasternal_long_subject_1.hdf5`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/A_cardiac/Verasonics_P2-4_parasternal_long_subject_1.hdf5), reconstructed from the raw channel data with `reconstruct.py`.*
+
 ## Dataset Description
 
 Part of the **UltraSound ToolBox (USTB) Channel Capture Collection** (see the [collection card](../README.md)).

oslo/B_carotid/README.md

@@ -19,6 +19,10 @@ size_categories:
 
 # USTB - In-vivo Carotid (Verasonics L7-4)
 
+![Focused B-mode of a carotid cross-section](assets/hero.png)
+
+*First frame of [`L7_FI_carotid_cross_1.hdf5`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/B_carotid/L7_FI_carotid_cross_1.hdf5), reconstructed from the raw channel data with `reconstruct.py`.*
+
 ## Dataset Description
 
 Part of the **UltraSound ToolBox (USTB) Channel Capture Collection** (see the [collection card](../README.md)).

oslo/C_verasonics_phantom/README.md

@@ -18,6 +18,10 @@ size_categories:
 
 # USTB - Phantom (Verasonics L7-4 / P4)
 
+![Phased-array sector B-mode of a cyst phantom](assets/hero.png)
+
+*First frame of [`FI_P4_cysts_center.hdf5`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/C_verasonics_phantom/FI_P4_cysts_center.hdf5), reconstructed from the raw channel data with `reconstruct.py`.*
+
 ## Dataset Description
 
 Part of the **UltraSound ToolBox (USTB) Channel Capture Collection** (see the [collection card](../README.md)).

oslo/D_alpinion_phantom/README.md

@@ -18,6 +18,10 @@ size_categories:
 
 # USTB - Phantom (Alpinion L3-8)
 
+![Plane-wave compounded B-mode of hypoechoic cysts](assets/hero.png)
+
+*First frame of [`Alpinion_L3-8_CPWC_hypoechoic.hdf5`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/D_alpinion_phantom/Alpinion_L3-8_CPWC_hypoechoic.hdf5), reconstructed from the raw channel data with `reconstruct.py`.*
+
 ## Dataset Description
 
 Part of the **UltraSound ToolBox (USTB) Channel Capture Collection** (see the [collection card](../README.md)).

oslo/E_simulation/README.md

@@ -19,6 +19,10 @@ size_categories:
 
 # USTB - Simulation (Field II)
 
+![B-mode of the PICMUS numerical phantom](assets/hero.png)
+
+*First frame of [`PICMUS_numerical_calib_v2.hdf5`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/E_simulation/PICMUS_numerical_calib_v2.hdf5), reconstructed from the raw channel data with `reconstruct.py`.*
+
 ## Dataset Description
 
 Part of the **UltraSound ToolBox (USTB) Channel Capture Collection** (see the [collection card](../README.md)).

oslo/F_motion/README.md

@@ -19,6 +19,10 @@ size_categories:
 
 # USTB - Motion Estimation (SWE / ARFI, Verasonics L7-4)
 
+![Shear waves travelling outward after an acoustic push](assets/hero.gif)
+
+*First push-track sequence (frames 1-49) of [`SWE_L7_type_III.hdf5`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/F_motion/SWE_L7_type_III.hdf5): B-mode (left) and axial displacement between consecutive frames (right), a lag-one autocorrelation (Kasai) estimate on the IQ beamformed with `pipeline.yaml`. The displacement estimate is not part of the reference pipeline.*
+
 ## Dataset Description
 
 Part of the **UltraSound ToolBox (USTB) Channel Capture Collection** (see the [collection card](../README.md)).

oslo/README.md

@@ -18,9 +18,9 @@ size_categories:
 
 # UltraSound ToolBox (USTB) Channel Capture Collection
 
-![Focused sector B-mode of an apical four-chamber view](assets/Verasonics_P2-4_apical_four_chamber_subject_1_zea_bmode.png)
+![B-modes from five of the six sub-datasets: in-vivo cardiac, in-vivo carotid, Verasonics and Alpinion phantoms, and simulation](assets/hero.png)
 
-*Apical four-chamber view reconstructed from the raw channel data, [`A_cardiac/Verasonics_P2-4_apical_four_chamber_subject_1.hdf5`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/A_cardiac/Verasonics_P2-4_apical_four_chamber_subject_1.hdf5).*
+*First frames reconstructed from the raw channel data with `reconstruct.py`. Top: [`A_cardiac/Verasonics_P2-4_parasternal_long_subject_1`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/A_cardiac/Verasonics_P2-4_parasternal_long_subject_1.hdf5), [`A_cardiac/Verasonics_P2-4_apical_four_chamber_subject_1`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/A_cardiac/Verasonics_P2-4_apical_four_chamber_subject_1.hdf5), [`C_verasonics_phantom/FI_P4_cysts_center`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/C_verasonics_phantom/FI_P4_cysts_center.hdf5). Bottom: [`B_carotid/L7_FI_carotid_cross_1`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/B_carotid/L7_FI_carotid_cross_1.hdf5), [`C_verasonics_phantom/L7_FI_Verasonics_CIRS`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/C_verasonics_phantom/L7_FI_Verasonics_CIRS.hdf5), [`D_alpinion_phantom/Alpinion_L3-8_CPWC_hypoechoic`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/D_alpinion_phantom/Alpinion_L3-8_CPWC_hypoechoic.hdf5), [`E_simulation/PICMUS_numerical_calib_v2`](https://huggingface.co/datasets/nvidia/OpenH-RF/blob/main/oslo/E_simulation/PICMUS_numerical_calib_v2.hdf5). Panels are scaled to a common height per row, not to a common physical scale.*
 
 ## Dataset Description